This application was reviewed at the February 2-4, 1978 meeting of the National Heart, Lung, and Blood Advisory Council and although favorably recommended was not funded. The application is hereby resubmitted revised in accordance with the Council's budget recommendations. The comments regarding the technical aspects of the proposal were helpful and greatly appreciated; however, after considering them the applicant believes that the techniques and procedures should remain as stated originally. The overall objective of long-term goal of this proposed research is the theoretical and clinical evaluations of the electrical impedance technique as a simple, harmless, non-invasive, and continuous means of quantitating and monitoring intrathoracic fluids, cardiac function, and respired volume in man and animals. Previous research in our laboratory (and others) has shown the feasibility of using the impedance technique for assessing respired volume, cardiac output, and intrathoracic fluid accumulation (pleural effusion, pericardial effusion, and pulmonary edema). In the course of our investigation of intrathoracic fluids, it was found, from ancillary experiments in four dogs, that the presence of intrathoracic fluid appeared to modify the impedance waveform in a manner such that values of cardiac output calculated from impedance were considerably lower than values measured simultaneously by means of an electromagnetic flow probe on the ascending aorta. The interaction of thoracic fluids, tissue edema, and PEEP on the measurement of respired volume, stroke volume, and cardiac output by electrical impedance requires investigation since one of the most attractive applications of the impedance technique is for quantitating and continuously monitoring these physiological variables in the trauma or intensive care unit.